Ultrasensitive C-reactive protein is abbreviated as CRP, and the normal value is 0-5mg/L. C-reactive protein is an acute reaction when complexes are formed by the reaction of C polysaccharide of Streptococcus pneumoniae, and it is easy to be abnormally elevated when some diseases occur. For example, various infections, bronchitis, lung infection, nephritis, infective endocarditis, urinary tract infection, connective tissue disease, tumor disease, and rheumatoid immune system diseases can cause this index to rise, so this index does not have obvious specificity. When the above index is elevated, it is necessary to carry out the relevant examination and further treatment according to the patient’s symptoms, signs and auxiliary examination. To ensure the accuracy of ultrasensitive C-reactive protein in the morning of the next day, it is necessary not to eat greasy food or drink water after 12 o’clock at night on the day before the reactive protein test.